The present invention relates to an image display system such as a personal computer having image processing functions including resolution adjustment, edge enhancement and gradation characteristic control, and an image display method. More particularly, the present invention concerns control for reducing generation of a false color.
FIGS. 5A and 5B are views for explaining a technique for increasing an apparent resolution. In the figures, one rectangle denotes one of pixel elements of a display panel (e.g., a liquid crystal panel), and a number given in each rectangle denotes a signal level (in units of %) of an image signal to display the pixel element. In the display panel, three adjacent pixel elements of red (R), green (G) and blue (B) constitute a single pixel. Such a display method in which a pixel is used as a minimum unit (for example, colors of R, G and B have all a signal level of 100%) as shown in FIG. 5A can be changed to a display method in which a pixel element is used as a minimum unit (for example, in the units of (R, G, B, R) or (G, B, R, G) or (B, R, G, B)), as shown in FIG. 5B. When such a display method as shown in FIG. 5B, in which a pixel element is used as a minimum unit, is employed, an apparent resolution can be improved.
FIGS. 6A and 6B are graphs for explaining the interpolating processing of an image signal. In the figures, reference symbols P1, P2, P3, P12 and P23 denote pixels arranged on a display panel respectively, and each pixel is made up of three colors R, G and B (i.e., three pixel elements). A vertical axis or ordinate in the figure denotes a level (in units of %) of an image signal used to display each pixel element. The image signal for displaying the three pixels P1, P2 and P3 is subjected to interpolating processing as shown in FIG. 6A to form an image signal for displaying pixels P12 and P23 as shown in FIG. 6B. The signal level of the pixel P12 corresponds to an average (50%) of the signal level (0%) of the pixel P1 and the signal level (100%) of the pixel P2, whereas the signal level of the pixel P23 corresponds to an average (50%) of the signal level (100%) of the pixel P2 and the signal level (0%) of the pixel P3. Even when the number (e.g., 800xc3x97600 dots) of pixels in pixel data generated (or inputted) through such interpolating processing becomes different from the display pixel number (e.g., 1024xc3x97768 dots) of a display panel, the pixel data can be displayed on the entire area of the display panel.
However, when such a display method in which a pixel element is used as a minimum unit (to increase an apparent resolution) as shown in FIG. 5B is carried out simultaneously with such interpolating processing of the image signal as shown in FIG. 6B, this involves a problem that such a color appears that should not be perceived at a location away from a suitable display position on the display panel, or a problem that a false color is generated that a color perceived different from its suitable color is displayed.
FIGS. 7A and 7B are graphs for explaining why a false color becomes remarkable when the interpolating processing of an image signal and the operation of increasing an apparent resolution are carried out at the same time. In the figures, reference symbols P01, P1, P2, P3, P12 and P23 denote pixels arranged on the display panel respectively. Further, a vertical axis or ordinate denotes the level of an image signal for displaying pixel elements (in units of %). When an image made up of pixel elements B, R, G and B having signal levels of 40, 100, 100 and 60 respectively is subjected to interpolating processing as shown in FIG. 7A, a pixel element B having a signal level of 20% appears in the pixel P01 at a position away from those of the other pixel elements as shown in FIG. 7B. Due to the pixel element appearing at such a distant position, a user perceives the appearance of an unnatural color.
It is therefore an object of the present invention to provide an image display system and an image display method that can reduce generation of a false color.
According to one aspect of the present invention, an image display system comprises: a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; a pixel data generator which generates pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels; a pixel element data generator which converts the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors; and a controller which selects any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein when selecting the second display mode, the controller sets a pixel number of the pixel data generated in the pixel data generator so as to coincide with a display pixel number of the display unit.
According to another aspect of the present invention, an image display system comprises: a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; a pixel data generator which generates pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels; an operating unit, through which an operator designates a pixel number of the pixel data generated in the pixel data generator; a pixel element data generator which converts the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors; and a controller which selects any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein when the second display mode is being selected and a value different from a display pixel number of the display unit is designated as a pixel number of the pixel data generated in the pixel data generator through the operating unit, the controller changes the current display mode to the first display mode.
According to further aspect of the present invention, an image display system comprises: a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; a pixel data generator which generates pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels; a pixel element data generator which converts the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors; an edge enhancement processor which performs image processing to enhance an edge of an image to be displayed on the display unit; and a controller which selects any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein the controller causes the edge enhancement processor not to perform the image processing when the second display mode is being selected.
According to further aspect of the present invention, an image display system comprises: a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; a pixel data generator which generates pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels; a pixel element data generator which converts the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors; a gradation characteristic controller which controls a gradation characteristic of the image to be displayed on the display unit; and a controller which selects any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein when selecting the second display mode, the controller controls operation of the gradation characteristic controller in such a manner that the gradation characteristic of the image to be displayed on the display unit is changed to a characteristic suitable for processing contents of the pixel element data generator.
According to further aspect of the present invention, a method for displaying an image, which is used in an image display system comprising a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; the method comprises: generating pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels by a pixel data generator; converting the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors by a pixel element data generator; and selecting any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein when selecting the second display mode, a pixel number of the pixel data generated in the pixel data generator is set so as to coincide with a display pixel number of the display unit.
According to further aspect of the present invention, a method for displaying an image, which is used in an image display system comprising a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; the method comprises: generating pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels by a pixel data generator; designating a pixel number of the pixel data generated in the pixel data generator by an operator through an operating unit; converting the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors by a pixel element data generator; and selecting any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein when the second display mode is being selected and a value different from a display pixel number of the display unit is designated as a pixel number of the pixel data generated in the pixel data generator through the operating unit, the current display mode is changed to the first display mode.
According to further aspect of the present invention, a method for displaying an image, which is used in an image display system comprising a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; the method comprises: generating pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels by a pixel data generator; converting the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors by a pixel element data generator; performing image processing to enhance an edge of an image to be displayed on the display unit by an edge enhancement processor; and selecting any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein the edge enhancement processor does not perform the image processing when the second display mode is being selected.
According to further aspect of the present invention, a method for displaying an image, which is used in an image display system comprising a display unit which includes regularly arranged red, green and blue pixel elements and which changes a displaying state of the pixel elements to display an image; the method comprises: generating pixel data consisting of three items of first pixel element data corresponding to red, green and blue signal levels by a pixel data generator; converting the pixel data into several items of second pixel element data as a minimum unit data corresponding to the signal levels of the respective colors by a pixel element data generator; controlling a gradation characteristic of the image to be displayed on the display unit by a gradation characteristic controller; and selecting any one of a first display mode of displaying an image on the display unit on the basis of the pixel data outputted from the pixel data generator and a second display mode of displaying an image on the display unit on the basis of the second pixel element data generated in the pixel element data generator, wherein when selecting the second display mode, the gradation characteristic controller operates in such a manner that the gradation characteristic of the image to be displayed on the display unit is changed to a characteristic suitable for processing contents of the pixel element data generator.